XCFHandler.php

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<?php
class XCFHandler extends BitmapHandler {
    public function mustRender( $file ) {
        return true;
    }

    public function getThumbType( $ext, $mime, $params = null ) {
        return [ 'png', 'image/png' ];
    }

    function getImageSize( $image, $filename ) {
        $header = self::getXCFMetaData( $filename );
        if ( !$header ) {
            return false;
        }

        # Forge a return array containing metadata information just like getimagesize()
        # See PHP documentation at: https://www.php.net/getimagesize
        return [
            0 => $header['width'],
            1 => $header['height'],
            2 => null, # IMAGETYPE constant, none exist for XCF.
            3 => "height=\"{$header['height']}\" width=\"{$header['width']}\"",
            'mime' => 'image/x-xcf',
            'channels' => null,
            'bits' => 8, # Always 8-bits per color
        ];
    }

    static function getXCFMetaData( $filename ) {
        # Decode master structure
        $f = fopen( $filename, 'rb' );
        if ( !$f ) {
            return false;
        }
        # The image structure always starts at offset 0 in the XCF file.
        # So we just read it :-)
        $binaryHeader = fread( $f, 26 );
        fclose( $f );

        try {
            $header = wfUnpack(
                "A9magic" . # A: space padded
                    "/a5version" . # a: zero padded
                    "/Nwidth" . # \
                    "/Nheight" . # N: unsigned long 32bit big endian
                    "/Nbase_type", # /
                $binaryHeader
            );
        } catch ( Exception $mwe ) {
            return false;
        }

        # Check values
        if ( $header['magic'] !== 'gimp xcf' ) {
            wfDebug( __METHOD__ . " '$filename' has invalid magic signature.\n" );

            return false;
        }
        # TODO: we might want to check for sane values of width and height

        wfDebug( __METHOD__ .
            ": canvas size of '$filename' is {$header['width']} x {$header['height']} px\n" );

        return $header;
    }

    public function getMetadata( $file, $filename ) {
        $header = self::getXCFMetaData( $filename );
        $metadata = [];
        if ( $header ) {
            // Try to be consistent with the names used by PNG files.
            // Unclear from base media type if it has an alpha layer,
            // so just assume that it does since it "potentially" could.
            switch ( $header['base_type'] ) {
                case 0:
                    $metadata['colorType'] = 'truecolour-alpha';
                    break;
                case 1:
                    $metadata['colorType'] = 'greyscale-alpha';
                    break;
                case 2:
                    $metadata['colorType'] = 'index-coloured';
                    break;
                default:
                    $metadata['colorType'] = 'unknown';
            }
        } else {
            // Marker to prevent repeated attempted extraction
            $metadata['error'] = true;
        }
        return serialize( $metadata );
    }

    public function isMetadataValid( $file, $metadata ) {
        if ( !$metadata ) {
            // Old metadata when we just put an empty string in there
            return self::METADATA_BAD;
        } else {
            return self::METADATA_GOOD;
        }
    }

    protected function getScalerType( $dstPath, $checkDstPath = true ) {
        return "im";
    }

    public function canRender( $file ) {
        Wikimedia\suppressWarnings();
        $xcfMeta = unserialize( $file->getMetadata() );
        Wikimedia\restoreWarnings();
        if ( isset( $xcfMeta['colorType'] ) && $xcfMeta['colorType'] === 'index-coloured' ) {
            return false;
        }
        return parent::canRender( $file );
    }
}